Geographic analysis of Red List Rhododendron (Ericaceae) taxa by country of origin identifies priorities for ex situ conservation

Abstract

A Red List assessment is insufficient to determine priorities for ex situ conservation in large genera such as Rhododendron, where there may be hundreds of taxa in any one Red List category. We have utilised an analysis of the geographic origins of 1 215 taxa of Rhododendron (Ericaceae) as a method to prioritise Red List taxa for ex situ conservation. This analysis includes descriptions of distribution and endemism by country of origin, analysis of the incidence of the 715 Red List taxa by country of origin, and determination of the extent to which taxa from each country of origin are in cultivation. We determined that of 30 countries of origin and a 'Europe' aggregate, 24 origins contain Red List taxa. Of those 24 origins, 17 origins and 'Europe' have greater than 75 % of Red List taxa 'in cultivation', as defined in this study, so that Target 8 of the Global Strategy for Plant Conservation has theoretically been met. However, for some of these origins the number of each taxon held 'in cultivation' is very low and genetic diversity is likely to be poor. The remaining six countries of origin have less than 75 % of Red List Rhododendron taxa recorded 'in cultivation' (Indonesia (28 %), Papua New Guinea (29 %), Malaysia (59 %), China (60 %), Japan (62 %) and Solomon Islands (0 %)). Analysis of a set of Red List factors and 'not in cultivation' factors reveals that Red List taxa from Indonesia, China and Papua New Guinea should take priority for ex situ conservation.

Allelopathic potential and allelochemical composition in different soil layers of Rhododendron delavayi forest, southwest China

“…The Rhododendron is the largest genus in Ericaceae family with approximately 1,000 species. These plants are mainly distributed in Asia and more than 650 species are found in China (MacKay and Gardiner, 2017). Certain Rhododendron species exert allelopathic effects on other plant species, and through this mechanism, they can form dominant communities.…”

Influences of Three Oidiodendron maius Isolates and Two Inorganic Nitrogen Sources on the Growth of Rhododendron kanehirae

“…The genus Rhododendron belongs to the family Ericaceae (heath family), with as many as 1024 species, and consists of 850 -1,000 subspecies (Li et al, 1998;Fayaz, 2012). There are 23 native Rhododendron species in Taiwan, of these, 16 (70%) are endemic (Gibbs et al, 2011;Argent, 2015;MacKay and Gardiner, 2017). One of the endemic species, R. kanehirae, is now only present in the wild, and a small population is distributed along Beishih Brook in north Taiwan (Tseng, 1993).…”

Phytophthora cinnamomi causing root rot on Rhododendron lapponicum and control it using potential biocontrol agents

“…Due to its high horticultural value, it has been widely cultivated, but with climate change, habitat differences, and disease and insect infestations, the number of some species has been reduced to the verge of extinction, resulting in the decline of species diversity and serious economic losses [10,11]. With the extension of planting time and scale, a new disease with symptoms of root rot was observed in Yunnan province, China.…”